Electric control system



p 17, 1940- D. c. HOFFMANN ELECTRIC CONTROL SYSTEM Filed Jan. 11, 1940 %HASTER PHASE SHIFTER TU CIRCUIT 1 Inventor- Daniel C. Hoffrnann b y His Attorney.

Patented Sept. 17, 1940 UNITED STATES PATENT OFFICE ELECTRIC CONTROL SYSTEM Daniel C. Hoifmann, Yeadon, Pa., assignmto General Electric Company, a. corporation 0! New York Application January 11, 1940, Serial No. 313,385

6 Claims.

My invention relates to electric control systems and more'particularly to control circuits for energizing the control members of electric valve apparatus of the type employing ionizable 5 mediums such as gases or vapors.

It is frequently desirable in the control of electric valve translating apparatus, where continuity of service is important, to provide systems which assure grid control voltage. In ac cordance with the teachings of my invention described hereinafter, I provide a new and im proved control system which is adaptable for energicing the grids or contrcl members of alientric valve apparatus.

it is a new am mnrcved control system.

fit another object of my invent on to vide a new anti improved control SYSiL-Blll for as suring the neirgization of an electric ci'rccit or e dwrce in the event of failure cow of my inventio pro supply van? t e of a can source a r us transferor voltage wit" rther of my and impreved grin suit 4 e transiating appwattc co and auto tic traieier is eitecterl from one M some without appreciable over w one the sources fails in wine "lrefiy stated, in illustraterl emit n I provide an. automatic A site? or 'tElI'OW-QVQI system the energization of an eleci coking apparatus prevent overlap of the cor zections of sources to the grid circuits in the one of the sources fails. Other transfer 'atus is provided to permit manual trausthe grid power from one source to a secobject of my invention ti: provide 0nd source with appreciable overlap so that continuity of service is maintained.

For a better understanding of my invention, reference may be had to the following descriptime taken in connection with the accompanyzirawing, and its scope will be pointed out in the appended claims. The single figure of the eirawingdiagrammatically illustrates an emto iiment of my invention as applied to a. recti- ..-er system comprising two parallel-operating elect c valve means for effecting energization ct current load cireint from an alternatcit: illustrated as nslating system. "ill? load circuit i filing primary nary windings secondary windings, by internfncse eetiveiy, and the two connected by a third suitable circuit a connected between and the supply also in verting apps re'ciy of the type of anodes H, a plurality of or grids ii]. It

of using electric it, anal these suitable phase Mich may be or the try windings 712 and Jigs (E5 and iii, respeces negative unidirec as batteries iii, may Y cected in circuit v. the secondary windil, 524 and The T9 ary phase shifting vices it! and it may energized from. a ccmmen supply cir .i-it iii.

A master phase siiifier, such as a rotary phase shifting device 28, may be connected to eifect conjoint control or adjustment of the phases of the alternating components of voltage impressed on the grids I9 of electric valve means I and I6.

I Certain broad features of the system including a master phase shifter in conjunction with circuits energized by individual phase shifters is disclosed and claimed in copencling patent application Serial No. 266,398 of Donald R. Smith, filed April 6, 1939, and which is assigned to the assignee of the present application.

A suitable positioning means such as a direct current motor 29 may be employed to control the angular displacement of the master phase shifter 28 and to control thereby the phase of the voltages impressed on the grids i9.of electric valve means l5 and i6. I have shown diagrammatically a suitable relay 36 comprising an actuating coil 3i which may be connected to be responsive to an electrical conditioirof one of the associated circuits, such as the voltage of the direct current circuit 5, and comprises contacts 32 and 33 which control the direction of rotation of the motor 29 by controlling the polarity of the voltage impressed on the armature winding thereof. 7

I provide a control system for assuring energization of the excitation circuits of the electric valve means it: and i6 and for permitting manual transfer of the circuits from one source of supply voltage to another source of supply voltage. In the arrangement shown in the figure, I provide a plurality of sources of grid voltage 34 and 35, which may be alternating voltages, for the control members l3 of electric valve means i5 and I6. To efiect this selective energization of the excitation circuits from either source or from that source which is in condition for operation, I provide a pair of control contactors 36 and 3'! which connect either source 34 or 35 to the master phase shifter 23. The system is arranged so that the grids i9 will be supplied from one source until that source fails or until the operator shifts over to the other source by means of a manual control switch described hereinafter. If the source in use fails, the master phase shifter 28 will be disconnected instantly from that source and immediately connected to the other source without overlap. If the system effects the change from one source manually by means of the manual control switch, the master phase shifter 28 is connected to the selected source before it is disconnected from the other source, with overlap, thereby assuring continuity of grid power. I

Contactors 36 and 31 are provided with main contacts 38 and each comprises an actuating coil 39 and auxiliary contacts 4042. Contacts 40 I of contactors 36 and 31 serve as cross-interlocking means to prevent accidental simultaneous closure of these contactors, that is to prevent simultaneous closure when the transfer from one source to the other is effected automatically. Contacts 42 of contactor 31 are connected to shunt coil 39 of contactor 36 through contacts 51 of selector contactor 55 and contacts 53' of relay 49, whereas contacts 42 of contactor 36 are connected to shunt coil 39 of contactor 31 through contacts 60 of selector contactor 54 and contacts 53" of relay 5B.

As a means for initiating operation of the transfer from one source to a second source when the voltage of the connected source fails, I-provide suitable means, such as a pair of instantaneous under-voltage relays 43 and 44, to check the presence of normal three phase grid supply voltage. The relays 43 and 44 are arranged to be responsive to the three phase system of voltages of the sources 34 and 35, respectively.

Relays 43 and 44 are provided with auxiliary relays 41 and 48, respectively. Relays 41 and 48 are provided with contacts, the upper contacts, which are connected to serve as cross-interlocking means to prevent accidental simultaneous closure of relays 41 and 48. I also provide auxiliary relays 49 and 59, each of which includes contacts 5l53'. In addition, I provide selector control contactors 54 and 55 which selectively control the system to effect connection of either source 34 or 35 to the excitation or grid circuits. Each of the contactors 54 and 55 comprises an actuating coil 56 and contacts 5760. Contacts 58 of contactors 54 and 55 serve as means for modifying the action of contactors 36 and 31 and the associated relays 4'! and 48 to permit simultaneous closure of contactors 36 and 31 when it is desired to transfer from either one to the other of sources 34 and 35 with an appreciable overlap, thereby assuring continuity of power supply to the master phase shifter 28. Contacts 58 of the selector contactors 54 and 55 shunt contacts 43 of contactors 36 and 3'! so that the opening of the upper contacts of relays 41 and 48 will not drop out contactors 36 and 31.

As a. means for manually pie-selecting a source of grid power and for effecting operation of the selector contactors 36 and .31 to energize the excitation circuits from sources 34 or 35, I provide a manual switch 6i having contacts 62 and 63. Switch 6i may be biased to the open-circuit position. The various relays and contactors described above may be energized from an auxiliary source of current 64.

The operation of the system shown in the single figure of the drawing will be explained by considering the system when unidirectional current is being supplied to the direct current load circuit i from the alternating current supply circuit 2 through electric valve means l5 and i6. The individual phase shifters 2i) and 2i are adjusted to effect the desired division of load between the electric valve means i5 and I6 and to control the voltage of circuit I. It will be further understood that grid power is supplied to the master phase shifter 28 from source 34 through the contactor 36. Relays 43, 41, 49 and contactor 36 will be closed, that is, the actuating coils thereof will be energized. Of course, the switch 6| has been operated manually to engage momentarily contact 62 to effect closrue of the selector contactor 54. The manner in which these elements are closed may be explained as follows: Relay 43, of course, is closed, effecting energization of the actuating coil of auxiliary relay 4'! from circuit 64 through a circuit including contacts 59 of contactor 54, contacts 40 of contactor 31, and the upper contacts of relay 48. contacts of 41 energizes the coil of relay 49 through a circuit including the lower contacts of 41, contacts 40 of contactor 31 and the upper contacts of relay 48. Closure of contacts 53 of relay 49 energizes coil 39 of contactor 36, effecting Closure of the lower be in the closed position and relay 43 will be energized through the contacts of relay 44, contacts 53 of relay 50, contacts SI of relay 43, contacts 40 of contactor 36, and the upper contacts of relay 41. Relay 43 closes its lower contacts and energizes relay 50 which in turn energizes contactor 31. Contactor 31 connects the master phase shifter 28 to source 35. The electric valve 6 means l4 and I 5 thereupon resume load.

Upon failure of the connected source, the rectifiers will drop load momentarily but'load will be picked up when contactor 31 closes. The time interval that load is off will probably not exceed one second, depending upon the time delay on dropout of relay 49. I

If source 35 fails when it is supplying grid power, the equipment will operate to connect source 34 to the excitation circuits in a manner similar to that described abovefor transferring from source 34 to source 35.

The operation of the control system will next be explained when the operator wishes to initiate manually the transfer from source 34 to source 35. The manual switch 6i isoperatedto close contact 63 and held in the closed circuit position for about one second. Contacts 63 and 60 of selector contactor 55' pick up relay 43,

' which closes its lower contacts and picks up relay 50. Relay 5!! picks up contactor 31 which conmeets the master phase shifter 23 to source 35. At this time sources 34 and 35 are connected in parallel.

Contacts 58 of the selector contactor 66 shunt contacts 40 of contactor 31 and the upper con of .voltage to the grids.

tacts of relay 48, so that the opening 01 these contacts will not drop out contactor 36. As contact 51 of contactor'55 is closed, coil 38 of contactor 36 will be shunted by contacts 42 of contactor 31 when 31 closes. The current is limited by the resistance shown in series with contact 5B of contactor 65. Contactor 36 drops out,

disconnecting source 34. When the operator releases switch 6|, the relays return to the normal positions. The purpose of dropping out contactor 36 by shunting its coil 33 with contacts 42 of contactor 31 is to insure that contactor 36 will not drop out until after contactor 31 has actually closed. Thus, contactors 36 and 31 overlap and there is no interruption in the supply Furthermore, by this arrangement the length of time that both contacts are closed is kept at a minimum. The length of time that the two sources 34 and 35 are in parallel is yery short, amounting to the time of dropout of contactor 36 when its coil 33 is'shunted by contacts 42 and of contactor 31. This time is approximately 0.05 second.

To transfer the grid circuit back to source 34, the operator moves the switch arm of switch 31 to engage contact 62 for about one second. The operation of the system in eflecting transfer manually from source 36 to source 34 is substantially the same as that explained above in efiecting transfer manually from source 34 to source 35.

While I have shown multi-contact relays 64 and 55, controlled from a manual switch 6| having contacts}! and 63, it will be understood that a manually operable switch having a plurality of contacts could.be employed instead of relays 64, 66 and switch 6|.

Relays 41 and 43 are electrically cross-interlocked by means of the upper contactsthereot which are connected in the circuits of the relay coils. In addition, contactors 36 and 31 are I cross-interlocked by means of the contacts 40 which are connected in the circuits of coils 39. This interlocking prevents accidental simultaneous closure of contactors 36 and 31 and permits simultaneous closure only when intended during manual operation of switch 6|.

While I have shown and described my invention as applied to a particular systemof connections and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and

I, therefore, aim in the appended claims to cover.

all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

i. In combination, an electric circuit, a plurality of sources of current, a plurality of contactor means each associated with a difierenttactor means each associated with a diiferent one of said sources for connecting the associated source to said electric circuit and each comprising an actuating, coil, a plurality of under-voltage relays each associated with a different one of said sources for selectively controlling the energization of the actuating coils to disconnect a faulty source from said circuit and to connect a source of normal operating voltage to said circuit without appreciable overlap, manually operable means for preselecting a source of said sources which is to be connected to said circuit, and relay means to connect a second source to said circuit before the disconnection of a previously connected source when the transfer between the sources is efiected by said manually operable means.

3. In combination, an electric circuit, a plurality of sources of current, a plurality of contactor means each associated with a different one of said sources for selectively connecting the sources to said electric circuit and each comprising an actuating coil, a plurality of relay means each associated with a difierent one of said sources and each associated with a different one of said contactor means for controlling the energization of the actuating coils substantially instantaneously in response to the voltage of one of said sources to disconnect a faulty source and to connect a source of normal operating voltage v a previously connected source when the transfer between the sources is effected by said manually operable means.

4. In combination, an electric circuit, a plu rality of sources of current, a plurality of con-,

tactors each arranged to connect said electric circuit with a difierent one of said sources and each comprising an actuating coil, main contacts and two sets of auxiliary contacts, means for interconnecting one set of said auxiliary contacts tending to prevent simultaneous closure of any two contactors, means for interconnecting the second. sets of auxiliary contacts to shunt the actuating coil of another contactor to establish time-delay on drop-out of said another contactor, and means for disconnecting one source from said circuit. and connecting another source with appreciable overlap comprising said actuating coils and selective contactors for shunting said one set of auxiliary contacts.

'5. In combination, an electric circuit, two sources of current, a'pair of contactors each arranged to connect said electric circuit and a difierent one of said sources and each compris- :ing an actuating coil, main contacts and two sets of auxiliary contacts, means for interconnecting one set of said auxiliary contacts tending to prevent simultaneous closure of said contactors, means for interconnecting the second sets of auxiliary contacts. to s'nunt the actuating coil of the other contactor to establish a time-delay on drop-out of said other contactor, and means for disconnecting one source from said circuit and connecting the other source with appreciable overlap comprising said actuating coils and selective contactors for shunting the first mentioned set of auxiliary contacts.

6. In combination, an electric circuit, a plurality of sources of current, a plurality of contactors each arranged to connect said electric circuit and a diiIerent one of said sources and each comprising an actuating coil, main contacts and two sets of auxiliary contacts, means for interconnecting one set of said auxiliary contacts tending to prevent simultaneous closure of any two contactors, a plurality of voltage responsive relays each connected to a different one of said sources, means for interconnecting said voltage responsive relays and the second sets of auxiliary contacts to shunt the actusting coil oi another contactor to establish a time-delay on drop-out of said another contactor, and means for disconnecting a source to said. circuit and disconnecting said another source from said circuit with appreciable overlap comprising said actuating coils and selective contactors for shunting the one set of auxiliary contacts.

DANIEL C. HOEFMANN. 

